1. Field of the Invention
The present invention relates to a bottoming cycle system for converting a portion of heat from a heat source stream, especially, an exhaust stream from an internal combustion engine, into usable mechanical and/or electrical power.
More particularly, the present invention relates to a bottoming cycle system for converting a portion of heat from a heat source stream, especially, an exhaust stream from an internal combustion engine, into usable mechanical and/or electrical power, where the system includes a heat recovery vapor generator (HRVG) subsystem, a multi-stage energy conversion or turbine (T) subsystem and a condensation thermal compression subsystem (CTCSS) and where one or more of the streams exiting the stages of the turbine subsystem T are sent back through different portions of the HRVG to be warmed and/or cooled before being forwarded to the next stage of the turbine subsystem T. The turbine subsystem T includes at least a high pressure turbine or turbine stage (HPT) and a low pressure turbine or turbine stage (LPT) and preferably, an intermediate pressure turbine or turbine stage (IPT).
2. Description of the Related Art
In U.S. Pat. Nos. 5,095,708 and 5,572,871, power systems were presented that were designed to serve as bottoming cycles for combined cycle systems. These systems both had a specific feature which was the key to their high efficiency; both systems used intercooling of the working fluid in between turbine stages. Because the heat released during intercooling was recuperated, it was then used as an additional source of heating for the process of vaporization. This resulted in a drastic increase in the thermodynamical reversibility and correspondingly in higher efficiency of the power cycle.
However, in the prior art, this process of intercooling was performed in a special heat exchanger, a so-called “intercooler.” Such an intercooler requires that the streams of working fluid in both the tubes and the shell of the intercooler be at high pressure. Moreover, the intercooled stream in the prior art is in the form of a vapor, and therefore the heat transfer coefficient from the vapor to the intercooler tubes is low. As a result, such an intercooler must be a very large and very expensive high pressure heat exchanger. This in turn has a very negative impact on the economics of the entire system.
Thus, there is a need in the art for a system designed to utilize heat from heat sources having a wide range of temperatures and to convert a potion of energy from these heat sources into mechanical and/or electrical power.